Geo-Redundant and High Reliability Commercial Mobile Alert System (CMAS)

ABSTRACT

A Commercial Mobile Alert System (CMAS) providing redundant cell broadcast centers (CBC). Multiple CBCs are interfaced to any given base station controller (BSC) or radio network controller (RNC) to provide geo-redundancy and high availability so that the failure of one CBC or a cluster of CBCs at one site will not cause service interruption for the area controlled by the associated BSC or RNC or for the entire service area in the public land mobile network (PLMN) network. The BSC or RNC interfaces to multiple CBCs at multiple sites without changes to the otherwise conventionally existing BSC/RNC, 3GPP 23.041 standard architecture.

This application claims priority from U.S. Provisional Appl. No.61/136,693, filed Sep. 25, 2008, entitled “Multiple Cell BroadcastCenters (CBC) System”, by Mark Titus et al., the entirety of which isexpressly incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to wireless telecommunications, andmore particularly to wireless cell broadcast messaging for commercialand emergency services.

2. Background of the Related Art

Cell Broadcast (CB) messaging is a mobile technology feature defined bythe ETSI's GSM committee and is part of the GSM standard. It is alsoknown as Short Message Service—Cell Broadcast (SMS-CB). Cell Broadcastis designed for simultaneous delivery of messages to multiple users in aspecified area. Whereas the Short Message Service—Point to Point(SMS-PP) is a one-to-one and one-to-a-few service, Cell Broadcast is aone-to-many geographically focused messaging service. Cell Broadcastmessaging is also supported by UMTS, as defined by 3GPP.

Cell Broadcast is a mobile technology that allows a text or binarymessage to be defined and distributed to all mobile handsets and similardevices connected to a set of cells (i.e., within a designatedgeographical area). The broadcast range can be varied, from a singlecell to the entire network.

Whereas SMS messages are sent point-to-point, Cell Broadcast messagesare sent point-to-area. This means that one Cell Broadcast message canreach a huge number of mobile devices at once. In other words, CellBroadcast messages are directed to radio cells, rather than to aspecific mobile device. A Cell Broadcast message is an unconfirmed PUSHservice, meaning that the originator of the message does not know whohas received the message, allowing for services based on anonymity.

In Europe, most handsets do have cell broadcast capability, and themajor European operators have deployed the technology in their networks.

Cell broadcast elements (CBEs) are usually connected to a ContentCasting Center (CCC), which is in turn connected to a single CellBroadcast Center. Cell Broadcast messages are then sent from the singleCell Broadcast Centers to the cells. Advanced infrastructures make useof GIS-based interfaces for definition of the used areas.

As currently defined, Cell Broadcast message page comprises 82 octets,which, using the default character set, equates to 93 characters. Up to15 of these pages may be concatenated to form a Cell Broadcast message.Each page of such a CB message has the same message identifier(indicating the source of the message), and the same serial number.Using this information, the mobile telephone is able to identify andignore broadcasts of already received messages.

FIG. 6 depicts conventional Global System for Mobile Communications(GSM) cell broadcast architecture that is used today.

In particular, as shown in FIG. 6, in conventional GSM cell broadcastarchitecture, a base station controller (BSC) 1101 interfaces to asingle cell broadcast center (CBC) 1103 over a one-to-one interface1105.

FIG. 7 shows conventional Universal Mobile Telecommunications Service(UMTS) cell broadcast architecture that is used today.

In particular, as shown in FIG. 7, in conventional UMTS cell broadcastarchitecture, a radio network controller (RNC) 2201 interfaces to asingle cell broadcast center (CBC) 2203 over a one-to-one interface2205.

Thus, in both GSM cell broadcast systems as well as in UMTS cellbroadcast systems, base station controllers (BSCs) and radio networkcontrollers (RNCs) interface on a one-to-one basis with a dedicatedrespective cell broadcast center (CBC).

This one-to-one dedicated architecture is embodied in current cellbroadcast standard architecture defined for both GSM and UMTS networks.Thus, a base station controller (BSC), or a radio network controller(RNC), can only interface to one cell broadcast center (CBC). See, e.g.,requirements set forth in Section 6 of 3GPP TS 23.041—“The BSC/RNC shallinterface to only one CBC”.

The Commercial Mobile Alert System (CMAS) is an emerging, nationwidewarning system that utilizes cell phone SMS to alert the public ofemergencies. Using CMAS, as currently envisioned, three types ofemergencies will be relayed to the public: a disaster, imminent orongoing threats, and child abductions (Amber Alerts). As designed, agovernment agency generates an emergency message (e.g., from a FederalAlert Gateway) and sends it to participating carriers or serviceproviders, who then relay the emergency message to the public via SMS(or vibration or audio cues for the disabled).

SUMMARY OF THE INVENTION

In accordance with the principles of the present invention,geo-redundancy is provided in a commercial mobile alert system (CMAS) bya base station controller; and a plurality of cell broadcast centers(CBCs) interfaced to the base station controller. In this way,redundancy is provided in the CBC in a given geographical area.

In accordance with another aspect of the invention, a commercial mobilealert system (CMAS) comprises a cell broadcast entity to handle anemergency alert message to be transmitted via a cell broadcast center. Acell broadcast center (CBC) server farm comprising a plurality of CBCservers is configured to accept the emergency alert message from thecell broadcast entity. Either a base station controller (BSC) or a radionetwork controller (RNC) is in communication with the plurality of CBCservers. The BSC/RNC is configured to receive the emergency alertmessage from only one of the plurality of CBC servers.

In yet another aspect of the invention, global load balancing isachieved by distributing traffic between two commercial mobile alertsystem (CMAS) sites via a DNS name resolution process, comprisingquerying a primary domain name server (DNS) for an address of a contentmanagement service provider (CMSP) gateway. If the primary DNS is notavailable, a secondary DNS is queried. An address resolution request issent either to a first site load balancer, or to a second site loadbalancer, using a load balance scheme. A virtual IP is returned to aquerying source of an emergency alert message.

A method of global load balancing achieved by distributing trafficbetween two commercial mobile alert system (CMAS) sites via global loadbalancing in accordance with yet another aspect of the inventioncomprises a primary CMSP gateway at a first site, and a secondary CMSPgateway at a second site. A federal alert gateway is configured tobroadcast emergency alert messages to a first IP address associated withthe primary CMSP gateway, and with a second IP address associated withthe secondary CMSP gateway. In this way a first global load balancer atthe first site communicates directly with both the primary CMSP gatewayand the secondary CMSP gateway. A global load balance scheme is achievedwherein the load of emergency alert messaging is distributed across allCMSP servers.

A cell broadcast center regional approach in accordance with stillanother aspect, comprises assigning each of a plurality of cellbroadcast centers (CBCs) to a respective BSC/RNC of a specific region ofa public land mobile network (PLMN). Geo-targeting is performed bysending an emergency alert message to a BSC/RNC in a specific regionthat is in an alert target area of the emergency alert message. Theemergency alert message is dropped by a given CBC if the alert targetarea has no overlap with a region controlled by the given CBC. In thisway, CMSP gateway server farms always send alert messages received froma federal alert gateway to CBCs in all regions regardless of desiredtarget area of a given emergency alert message.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present invention will become apparent tothose skilled in the art from the following description with referenceto the drawings, in which:

FIG. 1 shows use of multiple CBCs deployed in active-active mode in acommercial mobile alert system (CMAS), in accordance with the principlesof the present invention.

FIG. 2 shows use of multiple CBCs deployed in active-standby mated-pairmode in a commercial mobile alert system (CMAS), in accordance with theprinciples of the present invention.

FIG. 3 shows global load balancing achieved by distributing trafficbetween two sites via a DNS name resolution process, in accordance withthe principles of the present invention.

FIG. 4 shows commercial mobile service provider (CMSP) gateway globalload balancing performed using geo-redundant global load balancer, inaccordance with the principles of the present invention.

FIG. 5 shows cell broadcast center (CSCs) assigned to different regionsof a public land mobile network (PLMN) network, i.e., a distributedsystem where each CBC is only connected to the BSC/RNCs of a specificregion, in accordance with the principles of the present invention.

FIG. 6 depicts conventional Global System for Mobile Communications(GSM) cell broadcast architecture that is used today.

FIG. 7 shows conventional Universal Mobile Telecommunications Service(UMTS) cell broadcast architecture that is used today.

FIG. 8 shows a conventional commercial mobile alert system (CMAS)architecture functional for use of emergency alert information passed ina GSM network.

FIG. 9 shows a conventional commercial mobile alert system (CMAS)architecture functional for use of emergency alert information passed ina UMTS network.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The Commercial Mobile Alert System (CMAS) currently proposed by theUnited States Federal Government utilizes the cell broadcastarchitecture defined 3GPP TS 23.041 in a GSM/UMTS environment. But thelimitations of BSC/RNC architecture in GSM/UMTS cell broadcastarchitecture does not allow deployment of multiple cell broadcastcenters (CBCs) with geo-redundancy and high availability.

Because of the limitations of conventional architecture that providesone-to-one interfacing between a BSC or RNC, and a single cell broadcastcenter (CBC), conventional cell broadcast centers (CBCs) cannot bedeployed in a load sharing (i.e., active-active) mode.

For NON-emergency cell broadcast services in a commercial mobile alertsystem (CMAS), it is conventionally acceptable to have a base stationcontroller (BSC) interface to only one cell broadcast center (CBC) (inthe case of a GSM cell broadcast architecture), or a radio networkcontroller (RNC) interface to only one CBC (in the case of a UMTS cellbroadcast architecture). But the present inventors have appreciated thatwhen a cell broadcast center (CBC) associated with its respective BSC orRNC goes down, the geographic area controlled by that BSC or RNC willlose cell broadcast service, and won't be capable at that time ofdelivering the emergency alert. For successful implementation of CMASfor use in wide-scale emergency situations, the present inventors haveappreciated that geo-redundancy techniques and architectures must beimplemented to allow high reliability and assurance that an emergencyalert message is received by all eligible mobile devices.

The present invention enables delivery of emergency alert informationusing a Commercial Mobile Alert System (CMAS). In accordance with theprinciples of the present invention, the present inventors provide(contrary to current standards) the use of multiple CBCs interfaced to agiven BSC or RNC, despite what would seem to conventionally bedetrimental aspects. Such contrary interfacing in accordance with thepresent invention provides an environment that supports geo-redundancyand high availability so that the failure of one CBC or a cluster ofCBCs at one site will not cause service interruption for the areacontrolled by the associated BSC or RNC or for the entire service areain the public land mobile network (PLMN) network.

The present invention enables a base station controller (BSC) or radionetwork controller (RNC) to importantly interface to multiple CBCs atmultiple sites without changes to the otherwise conventionally existingBSC/RNC, 3GPP 23.041 standard architecture. The present invention alsoprovides various geo-redundant and high availability solutions for CMASin which multiple CBCs are supported.

The present invention provides a geo-redundant and high availabilityCMAS system utilizing connection of the BSC/RNC to multiple CBCs.

FIG. 1 shows use of multiple CBCs deployed in active-active mode in acommercial mobile alert system (CMAS), in accordance with the principlesof the present invention.

In particular, as shown in FIG. 1, multiple CBCs 502 are deployed inactive-active mode. The CBCs in the CBC server farm 502 communicate withthe BSC/RNC(s) 504 through a Network Address Translation (NAT) device506 which presents a single Virtual IP (VIP) address to the BSC/RNC 504.The BSC/RNC 504 is configured with the CBC VIP and thus from theperspective of the BSC/RNC 504 there is only one CBC in the CBC serverfarm 502 and no change to the otherwise conventional BSC/RNC 504 isrequired.

For a procedure initiated by one of the CBCs in the CBC server farm 502,e.g. WRITE-UPDATE, the CBC 502 first establishes a TCP/IP connectionwith the BSC/RNC 504 through the NAT device 506 and then sends a requestmessage to the BSC/RNC 504. The BSC/RNC 504 returns a response messagepreferably via the same TCP/IP connection through NAT device 506 to theCBC that issued the request.

For a procedure initiated by one of the BSC/RNCs 504, e.g. FailureIndication, the BSC/RNC 504 establishes a TCP/IP connection with one ofthe CBCs in the CBC server farm 502 via the NAT device 506 using theconfigured CBC VIP. The TCP/IP connection request from the BSC/RNC 504first hits the NAT device 506 and the NAT device 506 in turn selects oneCBC in the CBC server farm 502 to connect to based on load andavailability of all CBCs in the CBC server farm 502.

In accordance with the principles of the invention, all CBCs at the samesite (e.g., in the CBC server farm 502) share the same database (DB)cluster and the DB clusters at different sites are synchronized. Cellsite health status information carried in the response message from theBSC/RNC 504, or unsolicited messages from the BSC/RNC 504, are saved inthe database and made available to all CBCs in the CBC server farm 502.

Simple implementation of multiple CBCs would otherwise send differentbroadcast messages to the same BSC/RNC 504. In accordance with thepresent invention, to ensure that the serial numbers contained in themessages on the CBC-BSC/RNC interface are unique across all CBCs, adifferent range of serial numbers is allocated to the CBCs, e.g., usingthe most significant bits of the serial number field as CBC ID. Forinstance, in the example of FIG. 1, the two most significant bits of theserial number can be used as CBC ID, where “00” as the two mostsignificant bits corresponds to a first CBC CBC1 in the CBC server farm502, “01” to a second CBC CBC2, “10” to a third CBC CBC3, etc.

The present invention ensures the uniqueness of message sequencenumbering on CMSP gateway-CBC interface. To this end, each messageissued by the CMSP gateway to the CBC contains a message sequence numberwhich may be an integer or a string. When there are multiple CMSPGateway servers active at the same time, it is important that themessages generated by them contain different message sequence numbers.In the case where the message sequence number is expressed as aninteger, uniqueness of the message sequence number is ensured byallocating a different range of message sequence numbers to each CMSPGateway server, so that each server looks at a message sequence numberpool which is mutually exclusive to the others. In the case that themessage sequence number is expressed as a string, uniqueness of messagesequence number is ensured by assignment of a unique server ID to eachserver, and inclusion of server ID in the message sequence number.

The uniqueness of the serial number on the CBC-BSC/RNC can be ensured byallocation of a different range of serial numbers to each CBC server, sothat each server looks at a serial number pool which is mutuallyexclusive to the others.

FIG. 2 shows use of multiple CBCs deployed in active-standby mated-pairmode in a commercial mobile alert system (CMAS), in accordance with theprinciples of the present invention.

In particular, as shown in FIG. 2, only one CBC in the CBCactive/standby mated pair 602 is active at any given time, Thus, fromthe perspective of the BSC/RNC 504, there appears to be only one CBC.

FIG. 3, FIG. 4 and FIG. 5 show a number of different geo-redundant andhigh availability implementations of CMAS using the inventive multipleCBC architecture configurations as shown in the embodiments of FIG. 1and FIG. 2 of the present invention.

In particular, FIG. 3 shows global load balancing achieved bydistributing traffic between two sites via a DNS name resolutionprocess, in accordance with the principles of the present invention.

In step 1 of FIG. 3, a Federal Alert Gateway 502 queries a primary DNS510 for the address of the content management service provider (CMSP)Gateway in the CMSP gateway server farm 514. If the primary DNS 510 isnot available, the Federal Alert Gateway 502 queries a secondary DNS520.

In step 2 of FIG. 3, the relevant DNS server sends an address resolutionrequest to a site load balancer 512 at Site A or a site load balancer522 at Site B using round robin techniques as a load balance scheme.

In step 3 of FIG. 3, the relevant site load balancer 512, 522 of theselected site serves as a DNS authoritative server. The relevant siteload balancer 512, 522 returns the local virtual IP to the relevant DNSserver 510, 520 if the local site can handle the traffic; otherwise, itreturns the virtual IP (VIP) of its peer site.

In step 4 of FIG. 3, the relevant DNS server 510, 520 returns thevirtual IP to the Federal Alert Gateway 502.

Accordingly, the relevant local site CBC load balancer 512, 522 equallydistributes the load across all servers in the local CMSP gateway serverfarm 514, 524. When the CBC load balancer equally distributes the loadacross all servers in the local CBC server farm 514, 524, if the entireCBC server farm 514, 524 is down, the relevant site CBC load balancer512, 522 forwards the traffic to its counterpart CBC load balancer 522,512 at the peer site.

To ensure the message sequence numbers on the CMSP gateway-CBC interfaceare unique across all CMSP gateway servers including servers of bothsites, the present invention allocates a different range of messagesequence numbers to the CMSP gateway servers if the message sequencenumber is an integer. If the message sequence number is expressed instring form, a unique server ID is assigned to each CMSP gateway server,and includes the server ID in the message sequence number.

The same approach shown and described with reference to FIG. 1 is usedto ensure that the serial numbers contained in the messages on theCBC-BSC/RNC interface are unique across all CBCs at both sites.

FIG. 4 shows commercial mobile service provider (CMSP) gateway globalload balancing performed using geo-redundant global load balancer, inaccordance with the principles of the present invention.

In particular, as shown in FIG. 4, CMSP Gateway global load balancing isaccomplished by using geo-redundant global load balancer architecture.In these embodiments, a Federal Alert Gateway 602 is configured withprimary and secondary CMSP Gateway IP addresses with one pointing to aglobal load balancer 612 at Site A, and the other to a global loadbalancer 622 at Site B. If/when the primary site goes down, the FederalAlter Gateway 602 switches to the geo-redundant site, In the example ofFIG. 4, commercial mobile service provider (CMSP) gateway server farms614, 624 at both sites are in active mode. The global load balancer 612,622 at each site is connected to all CMSP Gateway servers 614, 624 atboth sites, and distributes the load across all servers.

As opposed to using DNS Name Resolution process to achievegeo-redundancy and global load balancing as shown in FIG. 3,geo-redundant global load balancers are used in FIG. 4, in which:

The Federal Alert Gateway 602 is configured with primary and secondaryCMSP Gateway IP addresses with one pointing to a global load balancer612 at Site A, and the other to a global load balancer 622 at Site B.If/when the primary site goes down, the Federal Alert Gateway 602switches to the geo-redundant site.

Also, the global load balancer 612, 622 at each site is connected to allCMSP Gateway servers 614, 624 at both sites, and distributes the loadacross all servers.

FIG. 5 shows cell broadcast centers (CBCs) assigned to different regionsof a public land mobile network (PLMN) network, i.e., a distributedsystem where each CBC 740, 742, 744 is only connected to the BSC/RNCs ofa specific region 730, 732, 733, in accordance with the principles ofthe present invention.

In FIG. 5 cell broadcast centers (CBCs) are assigned to differentregions of a public land mobile network (PLMN) network, i.e., its adistributed system where each CBC is only connected to the BSC/RNCs of aspecific region of a PLMN network. (This is in contrast to theembodiments shown in FIG. 1 and FIG. 2 wherein each CBC connects to allBSC/RNCs in a PLMN network).

With the architecture of FIG. 5, CMSP gateway server farms 714, 724always send the alert message received from the Federal Alert Gateway702 to the CBCs 740, 742, 744 in all regions regardless of the targetarea of the alert message.

The CBC 740, 742, 744 of each region performs geo-targeting and sendsthe received alert message to the BSC/RNCs 730, 732, 733 in its ownregion that are in the target area of the alert message. The messagewill be dropped by a CBC if the alert target area has no overlap withthe region the CBC controls.

According to these embodiments of the present invention, a cellbroadcast center (CBC) active-standby mated pair is used for each region730, 732, 733. Alternatively, while disclosed in an active/standby mode,the CBC servers in the CBC server farms 740, 742, 740 may alternativelybe in active-active configuration in each region 730, 732, 734.

Also according to these embodiments of the invention, DNS nameresolution is used to support CMSP gateway global load balancing.Alternatively, CMSP Gateway global load balancing as shown in FIG. 4 maybe used.

According to the present invention, the CMSP gateway in the respectiveCMSP gateway server farms 714, 724 always send the alert messagereceived from the Federal Alert Gateway 702 to the CBCs 740, 742, 744 inall regions regardless of the target area of the alert message. The CBC740, 742, 744 of each region performs geo-targeting and sends thereceived alert message to the BSC/RNCs 730, 732, 733 in its own regionthat are in the target area of the alert message.

Since the mobile device may move from one region to another andtherefore may receive different alert messages from different regions,the same approach shown and described with respect to FIG. 1 is used toensure that the serial numbers contained in the messages on theCBC-BSC/RNC interface 750, 752, 754 are unique across all CBCs in allregions.

While the invention has been described with reference to the exemplaryembodiments thereof, those skilled in the art will be able to makevarious modifications to the described embodiments of the inventionwithout departing from the true spirit and scope of the invention.

1. In a commercial mobile alert system (CMAS), geo-redundancy providedby: a base station controller; and a plurality of cell broadcast centers(CBCs) interfaced to said base station controller; wherein redundancy isprovided in said CBC in a given geographical area. 2-16. (canceled)